In this article, I first elaborate and refine the Principle of Intention Agglomeration (PIA), which was introduced by Michael Bratman as “a natural constraint on intention”. According to the PIA, the intentions of a rational agent should be agglomerative. The proposed refinement of the PIA is not only in accordance with the spirit of Bratman’s planning theory of intention as well as consistency constraints for intentions rooted in the theory, but also reveals some deep rationales of practical rationality regarding resource-limited agents. Then I defend the PIA against various objections and counterexamples, showing that the refined PIA survives attacks based on both conceptual analyses and psychological considerations.